Work in FY-91 has included final analysis of data and publication or preparation of manuscripts from an investigation of the interaction of age and transderman estradiol replacement at 3 different doses and placebo in postmenopausal women. We measured effects of estrogen with and without progestin on basal growth hormone GH and insulin-like growth factor I (IGF- I), GH responds to GHRH, calciotropic and gonadotropic hormone regulation, and clinical symptoms. Findings include: (1) older women remain responsive to the bone-conserving action of estrogen; (2) estrogens' action to preserve bone mass appears to be independent of any modulation of GH, IGF-I, PTH, 1-25 dihydroxy vitamin D, or calcitonin secretion; (3) older (>65 y) women have no more side effects from estrogen replacement than younger postmenopausal women and tolerate minor side effects equally well. A new study comparing interactions of oral vs. transdermal estrogen with body composition, spontaneous pulsatile GH secretion and basal and stimulated IGF-I is currently underway. Another study of long term effects of combination estrogen/progestin therapy on bone, lipids, and clinical symptoms in women >65 is underway.